Liquid air energy storage system and method

Abstract

Disclosed are a liquid air energy storage (LAES) system and method, relating to the technical field of large-scale energy storage. By means of multiple discharge cryopumps, the system sequentially pressurizes liquid air of the LAES system during a discharge operation to a discharge target pressure before the liquid air is regasified, thereby preventing the loss of high-quality cold energy caused by pressurizing the liquid air to the discharge target pressure all at once, so that higher-quality cold energy can be obtained after first pressurization. Moreover, by means of using a low-temperature compressor during a LAES charging operation, and cooling ambient air before and after the low-temperature compressor to a cryogenic temperature, compression power can be greatly reduced, thereby improving the overall charging and discharging efficiency of the LAES system.

Description

Liquid air energy storage system and method

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. CN202410878738.1, filed on July 2, 2024, the contents of which are incorporated herein in their entirety as part of the present application. TECHNICAL FIELD

[0003] The present application belongs to the technical field of large-scale energy storage, and particularly relates to a liquid air energy storage system and method with high charging and discharging efficiency. BACKGROUND

[0004] Liquid air energy storage (LAES), as one of the energy storage technologies, its principle is to use low-cost off-peak electricity to absorb air from the environment, then cool it until it becomes a liquid for storage; and at the peak of electricity consumption, release the liquid air and increase the pressure and temperature, then enter the expander to do work and generate electricity, realizing off-peak peak use, which can play an important role in grid peak regulation.

[0005] In order to ensure the charging and discharging efficiency of the LAES system, the high and low quality cold energy in the released liquid air will be recovered during LAES discharging, for air liquefaction in subsequent LAES charging. Under normal circumstances, the released normal pressure liquid air will be directly pressurized to the target pressure of discharging, and then the cold energy released in the regasification process of the liquid air at this target pressure will be recovered.

[0006] The regasification (LNG-RG) process of liquefied natural gas can release a large amount of cold energy; these cold energies can be introduced into the LAES system to improve the liquefaction ratio of air under charging conditions and improve the charging and discharging efficiency of the LAES system. Under normal circumstances, the released liquefied natural gas will be directly pressurized to the target pressure of the natural gas under the regasification condition, and then the cold energy released in the regasification process of the liquefied natural gas at this target pressure will be recovered.

[0007] The target pressure of the regasification of liquid air is usually around 8MPa; if the target pressure is too low, it will negatively affect the discharging power, thereby reducing the charging and discharging efficiency; if the target pressure is too high, it will negatively affect the high-quality cold energy output in the regasification process, which may lead to a decrease in the liquefaction rate of ambient air under the charging condition of the LAES, an increase in the proportion of normal pressure backflow air, and a decrease in the charging and discharging efficiency.

[0008] The target pressure of the regasification of liquefied natural gas entering a natural gas transmission pipeline is usually 10 MPa; some designs first pressurize the liquefied natural gas to 20 MPa, and then expand and do work in the liquefied natural gas regasification process through a pressure difference of 20 MPa to 10 MPa.

[0009] However, the liquid-gas phase change temperature of liquid air and liquefied natural gas at atmospheric pressure is very low, and the cold energy close to this temperature is high-quality cold energy, which is a scarce resource for the LAES system. After pressurization, the cold energy output characteristics of liquid air and liquefied natural gas will change greatly, the phase change temperature will rise, the specific heat capacity will change slowly, and the quality of the output cold energy will decrease. The pressurization method of the prior art does not fully consider these factors, and there is a lot of room for optimization. SUMMARY

[0010] Therefore, one object of the present application is to provide a liquid air energy storage system to solve the problem of quality loss of cold energy recovery in the prior art liquid air energy storage system, resulting in poor charging and discharging efficiency of the system.

[0011] In some illustrative embodiments, the liquid air energy storage system comprises a low-temperature compressor, a low-temperature expander, at least two discharging low-temperature pumps, an air supercooling discharging heat exchanger, an air supercooling charging heat exchanger, an air supercooling tank, an air supercooling medium, a deep cooling discharging heat exchanger, a deep cooling charging heat exchanger, a deep cooling tank, and a deep cooling medium;

[0012] wherein, in the LAES discharging condition,

[0013] The liquid air is sequentially pressurized by the at least two discharging low-temperature pumps to reach the discharging target pressure before the liquid air regasification; the air supercooling medium is cooled to an air supercooling temperature by the air supercooling discharging heat exchanger after the liquid air is pressurized by a first discharging low-temperature pump among them; the air supercooling medium at the air supercooling temperature enters the air supercooling tank for storage; the deep cooling medium is cooled to a deep cooling temperature by the deep cooling discharging heat exchanger after the liquid air is pressurized by a second discharging low-temperature pump among them; the deep cooling medium at the deep cooling temperature enters the deep cooling tank for storage;

[0014] wherein, in the LAES charging condition,

[0015] The ambient air is compressed by the low-temperature compressor to the charging target pressure before liquefaction of the ambient air; the ambient air is cooled to the deep cooling temperature by the deep cooling charging heat exchanger using the deep cooling medium at the deep cooling temperature before and after entering the low-temperature compressor; the ambient air at the deep cooling temperature and reaching the charging target pressure is further cooled to the air supercooling temperature by the air supercooling charging heat exchanger using the air supercooling medium at the air supercooling temperature; the ambient air at the air supercooling temperature is converted into liquid air at atmospheric pressure by the low-temperature expander.

[0016] In some alternative embodiments, the liquid air energy storage system further comprises: a LNG sub-cooling charge heat exchanger, a LNG sub-cooling tank, a LNG sub-cooling medium and a natural gas regasification subsystem; the natural gas regasification subsystem comprises: at least two LNG cryogenic pumps, a LNG sub-cooling heat exchanger and a LNG deep cooling heat exchanger;

[0017] wherein, in the LNG regasification working condition,

[0018] the LNG is sequentially pressurized by the at least two LNG cryogenic pumps to reach a LNG target pressure before LNG regasification; the LNG sub-cooling medium is cooled to a LNG sub-cooling temperature by the LNG sub-cooling heat exchanger after the LNG is pressurized by a first LNG cryogenic pump among the at least two LNG cryogenic pumps; the LNG sub-cooling medium at the LNG sub-cooling temperature enters the LNG sub-cooling tank for storage; the deep cooling medium is cooled to a deep cooling temperature by the LNG deep cooling heat exchanger after the LNG is pressurized by a second LNG cryogenic pump among the at least two LNG cryogenic pumps; the deep cooling medium at the deep cooling temperature enters the deep cooling tank for storage;

[0019] wherein, in the LAES discharge working condition, the ambient air at the deep cooling temperature is cooled to an air sub-cooling temperature by the LNG sub-cooling charge heat exchanger using the LNG sub-cooling medium at the LNG sub-cooling temperature before reaching the charge target pressure;

[0020] wherein, the LNG sub-cooling temperature is lower than the deep cooling temperature and higher than the air sub-cooling temperature.

[0021] In some alternative embodiments, the discharge target pressure is higher than the charge target pressure.

[0022] In some alternative embodiments, the cryogenic compressor comprises a plurality of cryogenic compressors, and the deep cooling charge heat exchanger comprises a plurality of deep cooling charge heat exchangers, wherein the ambient air is sequentially multi-staged compressed by the plurality of cryogenic compressors to reach the target charge pressure, and the ambient air is cooled to the deep cooling temperature by the deep cooling charge heat exchanger using the deep cooling medium at the deep cooling temperature before and after entering each stage of the cryogenic compressor.

[0023] In some alternative embodiments, the air sub-cooling tank, the LNG sub-cooling tank and the deep cooling tank are respectively a pair of adiabatic low-pressure containers; the temperatures of the media stored in the cold-end containers of the air sub-cooling tank, the LNG sub-cooling tank and the deep cooling tank are respectively an air sub-cooling temperature, a LNG sub-cooling temperature and a deep cooling temperature; the air sub-cooling temperature is lower than the LNG sub-cooling temperature, and the LNG sub-cooling temperature is lower than the deep cooling temperature.

[0024] In some alternative embodiments, an LNG expander is further included, wherein the LNG target pressure is higher than the pressure of natural gas entering a natural gas pipeline network after regasification, and a pressure difference between the LNG target pressure and the pipeline network pressure is used to work by the LNG expander.

[0025] In some alternative embodiments, the air subcooling charge heat exchanger and / or the LNG subcooling heat exchanger are plate heat exchanger structures.

[0026] In some alternative embodiments, the number of the LNG cryogenic pumps is 3.

[0027] In some alternative embodiments, the deep cooling charge heat exchanger includes an LNG deep cooling charge heat exchanger at the inlet of the cryogenic compressor and an air deep cooling charge heat exchanger at the outlet of the cryogenic compressor; the deep cooling tank includes an air deep cooling tank and an LNG deep cooling tank which are independent of each other; the deep cooling discharge heat exchanger is an air deep cooling discharge heat exchanger; and the deep cooling medium includes an air deep cooling medium and an LNG deep cooling medium.

[0028] wherein, in the LAES discharge mode,

[0029] after the liquid air is pressurized by the second air subcooling pump therein, the air deep cooling medium is cooled to an air deep cooling temperature by the air deep cooling discharge heat exchanger; and the air deep cooling medium at the air deep cooling temperature is stored in the air deep cooling tank.

[0030] wherein, in the LNG regasification mode,

[0031] after the LNG is pressurized by the second LNG cryogenic pump therein, the LNG deep cooling medium is cooled to an LNG deep cooling temperature by the LNG subcooling heat exchanger; and the LNG deep cooling medium at the LNG deep cooling temperature is stored in the LNG deep cooling tank; wherein the air deep cooling temperature is lower than the LNG deep cooling temperature.

[0032] wherein, in the LAES discharge mode, the ambient air is cooled to a deep cooling temperature by a deep cooling charge heat exchanger using a deep cooling medium at a deep cooling temperature before and after the ambient air enters the cryogenic compressor, specifically including: the ambient air is cooled to an LNG deep cooling temperature by an LNG deep cooling charge heat exchanger using an LNG deep cooling medium at an LNG deep cooling temperature before and after the ambient air enters the cryogenic compressor and / or is cooled to an air deep cooling temperature by an air deep cooling charge heat exchanger using an air deep cooling medium at an air deep cooling temperature.

[0033] Another object of the present application is to provide a liquid air energy storage method to solve the technical problems in the prior art.

[0034] In some illustrative embodiments, the liquid air energy storage method includes: LAES discharge mode and LAES charging mode;

[0035] Under LAES discharge conditions, liquid air undergoes the following steps: C1, the liquid air is pressurized by a first discharge cryogenic pump; C2, the liquid air is cooled to its cryogenic temperature by an air cryogenic discharge heat exchanger; the cryogenic medium at this temperature is then stored in a cryogenic tank; C3, the liquid air is pressurized by a second discharge cryogenic pump to reach the discharge target pressure before re-vaporization; C4, the liquid air is cooled to its cryogenic temperature by a cryogenic discharge heat exchanger; the cryogenic medium at this temperature is then stored in a cryogenic tank.

[0036] Under LAES charging conditions, the ambient air undergoes the following steps: D1, the ambient air is compressed by a cryogenic compressor to the target charging pressure before liquefaction; wherein, before and after entering the cryogenic compressor, the ambient air is cooled to cryogenic temperature using a cryogenic medium at cryogenic temperature through a cryogenic charging heat exchanger; D2, the ambient air at the target charging pressure and cryogenic temperature is further cooled to ultra-cold air temperature using an ultra-cold air medium at ultra-cold air temperature through an ultra-cold air charging heat exchanger; D3, the ultra-cold air temperature ambient air is converted into liquid air at atmospheric pressure through a cryogenic expander;

[0037] The cold end temperature of the air-cooled tank is the air-cooled temperature, and the cold end temperature of the cryogenic tank is the cryogenic temperature; the air-cooled temperature is lower than the cryogenic temperature.

[0038] In some illustrative embodiments, the liquid air energy storage method further includes: LNG regasification process;

[0039] Under LNG regasification conditions, LNG undergoes the following steps: L1, LNG is pressurized by a first LNG cryogenic pump; L2, LNG is cooled to its cryogenic temperature by an LNG cryogenic heat exchanger; the cryogenic medium at this temperature is then stored in an LNG cryogenic tank; L3, LNG is pressurized by a second LNG cryogenic pump to reach the target pressure required for LNG regasification; L4, LNG is cooled to its cryogenic temperature by an LNG deep cryogenic heat exchanger; the cryogenic medium at this temperature is then stored in the cryogenic tank.

[0040] In the LAES discharging condition, the D2 comprises: D2-1, ambient air at a deep cooling temperature reaching a charging target pressure is cooled to an LNG supercooling temperature by using an LNG supercooling medium of LNG supercooling temperature through an LNG supercooling charging heat exchanger; D2-2, ambient air at the LNG supercooling temperature is further cooled to an air supercooling temperature by using an air supercooling medium of air supercooling temperature through an air supercooling charging heat exchanger; wherein the LNG supercooling temperature is lower than the deep cooling temperature and higher than the air supercooling temperature.

[0041] In some illustrative embodiments, the discharging target pressure is higher than the charging target pressure.

[0042] Compared with the prior art, the present application has the following advantages:

[0043] In the embodiments of the present application, the liquid air in the LAES system in the discharging condition is sequentially pressurized to the discharging target pressure before the gasification of the liquid air by using multiple discharging cryogenic pumps, so that the loss of high-quality cold energy caused by one-time pressurization of the liquid air to the discharging target pressure is avoided, and relatively higher-quality cold energy can be obtained after the first pressurization. Meanwhile, by using a cryogenic compressor in the LAES charging condition and cooling the ambient air before and after the cryogenic compressor to a deep cooling temperature, the compression power can be greatly reduced, and the overall charging and discharging efficiency of the LAES system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0044] Fig. 1 is a structure example one of the liquid air energy storage system in the embodiments of the present application;

[0045] Fig. 2 is a structure example two of the liquid air energy storage system in the embodiments of the present application;

[0046] Fig. 3 shows part of the unit nodes of the embodiment 2 of the present application.

[0047] The label explanation in Fig. 1 is as follows:

[0048] ambient compressor C1, heat exchanger charging-hot XC-H, air purification unit APU, heat exchanger charging-shallow cold XC-SC, first heat exchanger charging-deep cold XC1-DC, first low temperature compressor C2, second heat exchanger charging-deep cold XC2-DC, second low temperature compressor C3, third heat exchanger charging-deep cold XC3-DC, third low temperature compressor C4, fourth heat exchanger charging-deep cold XC4-DC, heat exchanger charging-LNG ultra cold XC-LUC, heat exchanger charging-air ultra cold XC-AUC, cryogenic pump CE, liquid air separator LAS, liquid air dewar LAD, first discharge cryogenic pump DCP1, heat exchanger discharging-air ultra cold XD-AUC, second discharge cryogenic pump DCP2, heat exchanger discharging-deep cold XD-DC, heat exchanger discharging-shallow cold XD-SC, heat exchanger discharging-hot XD-H, expander E1, heat storage tank (hot end D1-H,Cold End D2-H (Hot Dewar 2), Shallow Cold Tank (Hot End D1-SC (Shallow Cold Dewar 1), Cold End D2-SC (Shallow Cold Dewar 2)), Deep Cold Tank (Hot End D1-DC (Deep Cold Dewar 1), Cold End D2-DC (Deep Cold Dewar 2)), LNG Ultra Cold Tank (Hot End D1-LUC (LNG Ultra Cold Dewar 1), Cold End D2-LUC (LNG Ultra Cold Dewar 2)), Air Ultra Cold Tank (Hot End D1-AUC (Air Ultra Cold Dewar 1), Cold End D2-AUC (Air Ultra Cold Dewar 2)), First LNG Cryogenic Pump LCP1 (LNG Cryogenic Pump 1), LNG Ultra Cold Heat Exchanger XL-LUC, Second LNG Cryogenic Pump LCP2 (LNG Cryogenic Pump 2), LNG Deep Cold Heat Exchanger XL-DC (LNG Heat Exchanger-Deep Cold), Third LNG Cryogenic Pump LCP3 (LNG Cryogenic Pump 3), LNG Shallow Cold Heat Exchanger XL-SC (LNG Heat Exchanger-Shallow Cold), and LNG Expander EL (LNG Expander).

[0049] Supplementary markings in Fig. 2 explain:

[0050] a first LNG deep cold charging heat exchanger XC1-LDC (Heat Exchanger Charging 1-LNG Deep Cold), a second LNG deep cold charging heat exchanger XC2-LDC (Heat Exchanger Charging 2-LNG Deep Cold), a third LNG deep cold charging heat exchanger XC3-LDC (Heat Exchanger Charging 3-LNG Deep Cold), a fourth air deep cold charging heat exchanger XC4-ADC (Heat Exchanger Charging 4-Air Deep Cold), LNG deep cold tanks (hot end D1-LDC (LNG Deep Cold Dewar 1), cold end D2-LDC (LNG Deep Cold Dewar 2)), air deep cold tanks (hot end D1-ADC (Air Deep Cold Dewar 1), cold end D2-ADC (Air Deep Cold Dewar 2)), an air deep cold discharging heat exchanger XD-ADC (Heat Exchanger Discharging-Air Deep Cold). DETAILED DESCRIPTION

[0051] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall into the scope of protection of the present application.

[0052] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the meanings as commonly understood by one of ordinary skill in the art to which this application belongs. Unless specifically defined otherwise in the present application, the terms "first", "second", and similar terms do not imply any order, quantity, or importance, but are used to distinguish one element from another. The terms "comprises", "comprising", "includes", "including" and the like can be used in the sense of "including but not limited to". The terms "connected", "coupled", and the like can be used in the sense of physical or mechanical connection, or electrical connection, whether direct or indirect. In order to keep the following description of the embodiments of the present application clear and concise, known functions, known components, or known technical terms of the art are omitted in the following description of the embodiments of the present application. In the case of not conflicting with each other, each technical feature in the embodiments of the present application can be combined with each other, and the combined embodiment still falls within the scope of the present application.

[0053] In order to improve the overall charging and discharging efficiency of the liquid air energy storage system (LAES), the following design goals need to be met as much as possible: 1. For ambient air before low-temperature expansion under the charging condition of the LAES: A. The pressure is as high as possible; B. The temperature is as low as possible; C. The compression power is as low as possible. 2. For liquid air under the discharging condition of the LAES: D. The pressurization of the liquid air before regasification is as high as possible, so as to generate more expansion work; E. The temperature of the cold energy released during the regasification process is as low as possible, so as to reduce the temperature of the ambient air before entering the low-temperature expander for low-temperature expansion under the charging condition of the LAES as much as possible.

[0054] Among them, the combination of A and B can improve the liquefaction ratio of liquid air, and the purpose of C is to reduce the power consumption of system charging, E is the main prerequisite of B, A and C conflict with each other, D and E conflict with each other, therefore, how to coordinate the above A, B, C, D, E is an important optimization target for improving the charging and discharging efficiency of LAES.

[0055] In the prior art, under the discharging condition of the LAES, the released liquid air is directly pressurized to the discharging target pressure before regasification of the liquid air under the discharging condition, and then the cold energy released during the regasification process of the liquid air is recovered at the discharging target pressure. However, due to the pressurization process, the temperature of the liquid air increases, and the higher the pressure, the higher the temperature, which results in the decrease of the quality and total amount of cold energy recovery, which is the main problem of the conflict between D and E.

[0056] To this end, the application provides a liquid air energy storage system and method, in which the liquid air before regasification is gradually brought to the discharge target pressure before regasification of the liquid air in the discharge condition through two or more sequential pressurizations, so that relatively higher quality (relatively lower temperature) cold energy can be obtained after the first pressurization, and subsequent pressurizations ensure that the liquid air can reach the discharge target pressure before regasification of the liquid air in the discharge condition, thereby solving the conflict between D and E and achieving the B target; at the same time, in the charging condition of the LAES, the low-temperature compression can achieve the A and C targets.

[0057] The application discloses a liquid air energy storage system, and particularly, as shown in FIG. 1, which is a structural example one of the liquid air energy storage system in the application; the liquid air energy storage system comprises a low-temperature compressor (such as C2, C3 and C4), a low-temperature expander CE, at least two discharge low-temperature pumps (such as a first discharge low-temperature pump DCP1 and a second discharge low-temperature pump DCP2), an air supercooling discharge heat exchanger XD-AUC, an air supercooling charging heat exchanger XC-AUC, an air supercooling tank (a cold end D1-AUC and a hot end D2-AUC), an air supercooling medium, a deep cooling discharge heat exchanger XD-DC, a deep cooling charging heat exchanger (such as XC1-DC, XC2-DC, XC3-DC and XC4-DC), a deep cooling tank (a cold end D1-DC and a hot end D2-DC), a deep cooling medium and a liquid air storage tank LAD.

[0058] In the discharge condition of the LAES, the liquid air released from the liquid air storage tank LAD is sequentially pressurized by two or more discharge low-temperature pumps to reach the discharge target pressure before regasification of the liquid air; in the process, the liquid air is first pressurized by the first discharge low-temperature pump DCP1 and then enters the air supercooling discharge heat exchanger XD-AUC, and exchanges cold energy with the air supercooling medium in the air supercooling discharge heat exchanger XD-AUC to cool the air supercooling medium to an air supercooling temperature, and the air supercooling medium cooled to the air supercooling temperature enters the air supercooling tank to store the air supercooling energy; then the liquid air is secondarily pressurized by the second discharge low-temperature pump DCP2 and then enters the deep cooling discharge heat exchanger XD-DC, and exchanges cold energy with the deep cooling medium in the deep cooling discharge heat exchanger XD-DC to cool the deep cooling medium to a deep cooling temperature DCT, and the deep cooling medium cooled to the deep cooling temperature DCT enters the deep cooling tank to store the deep cooling energy;

[0059] In some embodiments, the air overcooling medium in the LAES discharging condition is guided from the hot end D2-AUC of the air overcooling tank into the air overcooling discharging heat exchanger XD-AUC, and after the cold energy exchange between the air overcooling medium and the liquid air, the air overcooling medium is discharged from the air overcooling discharging heat exchanger XD-AUC and stored in the cold end D1-AUC of the air overcooling tank. Similarly, the deep cooling medium in the LAES discharging condition is guided from the hot end D2-DC of the deep cooling tank into the deep cooling discharging heat exchanger XD-DC, and after the cold energy exchange between the deep cooling medium and the liquid air, the deep cooling medium is discharged from the air overcooling discharging heat exchanger XD-DC and stored in the cold end D1-AUC of the deep cooling tank.

[0060] In the above LAES discharging condition, the pressure of the liquid air after the first pressurization is lower than the discharging target pressure before the liquid air is gasified, so that the air overcooling energy with higher quality can be recovered, and the temperature of the ambient air before the low-temperature expansion in the LAES charging condition can be further reduced, thereby improving the overall charging and discharging efficiency.

[0061] In order to avoid the gasification of the liquid air during the recovery of the air overcooling energy and the deep cooling energy, the temperature of the liquid air after the recovery of the air overcooling energy is lower than the liquid-gas phase transition temperature of the liquid air after the first pressurization; similarly, the temperature of the liquid air after the recovery of the deep cooling energy is lower than the liquid-gas phase transition temperature of the liquid air after the second pressurization.

[0062] In addition, the liquid air after the recovery of the cold energy in the LAES discharging condition is gasified and then expanded by the expander E1 to convert the kinetic energy of the gasified air into electrical energy for power generation. In general, multi-stage expansion power generation is used, which is known in the art and is not the focus of the present application, and its description is omitted here.

[0063] In the LAES charging condition, the ambient air is compressed by the low-temperature compressor (such as C2, C3, C4) to the charging target pressure before the ambient air is liquefied; wherein the ambient air before and after entering the low-temperature compressor (such as C2, C3, C4) for low-temperature compression is exchanged with the deep cooling medium in the deep cooling charging heat exchanger (such as XC1-DC, XC2-DC, XC3-DC, XC4-DC), and the ambient air is cooled to the deep cooling temperature DCT by the deep cooling medium with the deep cooling energy DCE, and the ambient air after low-temperature compression and temperature cooling to the deep cooling temperature DCT enters the air overcooling charging heat exchanger XC-AUC, and is further exchanged with the air overcooling medium in the air overcooling charging heat exchanger XC-AUC, and the ambient air is cooled from the deep cooling temperature to the air overcooling temperature AUCT by the air overcooling medium with the air overcooling energy AUCE, and finally the ambient air cooled to the air overcooling temperature AUCT enters the low-temperature expander CE to be converted into liquid air at normal pressure and stored in the liquid air tank LAD.

[0064] In some embodiments, the air overcooling medium in the LAES charging mode is led out from the cold end D1-AUC of the air overcooling tank to the air overcooling charging heat exchanger XC-AUC, and after the cold energy exchange between the air overcooling medium and the liquid air, the air overcooling medium is discharged from the air overcooling charging heat exchanger XC-AUC and stored in the hot end D2-AUC of the air overcooling tank. Similarly, the deep cooling medium is led out from the cold end D1-DC of the deep cooling tank to the deep cooling charging heat exchanger XC-DC, and after the cold energy exchange between the deep cooling medium and the liquid air, the deep cooling medium is discharged from the deep cooling charging heat exchanger XC-DC and stored in the hot end D2-DC of the deep cooling tank.

[0065] In the above LAES charging mode, the low-temperature compressor is used, and the temperature of the ambient air before and after the low-temperature compressor is cooled to the deep cooling temperature, so that the compression power can be greatly reduced.

[0066] In the embodiment of the present application, the liquid air in the LAES discharging mode is sequentially pressurized by multiple discharge low-temperature pumps to reach the discharging target pressure before the liquid air is gasified, which avoids the loss of high-quality cold energy caused by the one-time pressurization of the liquid air to the discharging target pressure, so that relatively higher-quality cold energy can be obtained after the first pressurization. At the same time, in the LAES charging mode, the low-temperature compressor is used, and the ambient air before and after the low-temperature compressor is cooled to the deep cooling temperature, so that the compression power can be greatly reduced, thereby improving the overall charging and discharging efficiency of the LAES system.

[0067] In some embodiments, the low-temperature compressor in the embodiment of the present application can be a multi-stage low-temperature compressor group composed of multiple low-temperature compressors (for example, a first low-temperature compressor C2, a second low-temperature compressor C3, and a third low-temperature compressor C4), and the deep cooling charging heat exchanger includes multiple deep cooling charging heat exchangers (for example, a first deep cooling charging heat exchanger XC1-DC, a second deep cooling charging heat exchanger XC2-DC, a third deep cooling charging heat exchanger XC3-DC, and a fourth deep cooling charging heat exchanger XC4-DC).

[0068] The ambient air is sequentially multi-stage compressed by the multiple low-temperature compressors to reach the charging target pressure, and the ambient air before and after entering each low-temperature compressor is cooled to the deep cooling temperature by the deep cooling medium in the deep cooling charging heat exchanger.

[0069] The number of deep cooling charging heat exchangers should be greater than the number of low-temperature compressors, so as to realize the cooling treatment of the ambient air before and after the low-temperature compressors. Preferably, the number of deep cooling charging heat exchangers is one more than the number of low-temperature compressors, that is, one deep cooling charging heat exchanger is arranged at the inlet of each low-temperature compressor, and one deep cooling charging heat exchanger is arranged at the outlet of the last low-temperature compressor.

[0070] The embodiment makes full use of deep cooling to realize multi-stage low-temperature compression in the charging mode of the LAES system, which can greatly improve the low-temperature compression efficiency and reduce the power consumption of the air compression process.

[0071] In some embodiments, the liquid air energy storage system in the embodiment of the present application can further include a normal-temperature compressor C1 for first compressing ambient air at normal temperature before low-temperature compression of the ambient air in the LAES charging process, thereby increasing the pressure of the ambient air.

[0072] In some embodiments, the liquid air energy storage system in the embodiment of the present application can further include a heat storage charging heat exchanger XC-H, a heat storage discharging heat exchanger XD-H, a heat storage tank (such as a hot end D2-H and a cold end D1-H), and a heat exchange medium; wherein the heat exchange medium obtains compression heat energy from the ambient air after normal-temperature compression in the heat storage charging heat exchanger XC-H in the LAES charging mode and stores the compression heat energy into the heat storage tank to realize storage of the compression heat energy; and the heat exchange medium outputs the compression heat energy to the regasification air in the heat storage discharging heat exchanger XD-H in the LAES discharging mode, thereby increasing the expansion temperature of the regasification air and increasing the kinetic energy thereof. In the LAES charging mode, the heat exchange medium is led out from the cold end D1-H of the heat storage tank into the heat storage charging heat exchanger HC-H, and after heat energy exchange with the ambient air, enters the hot end D2-H of the heat storage tank; in the LAES discharging mode, the heat exchange medium flows in the opposite direction.

[0073] In some embodiments, the liquid air energy storage system in the embodiment of the present application can further utilize an external heat source to further increase the expansion temperature of the regasification air in the discharging mode; wherein the external heat source is not limited to ambient air, seawater, solar energy, or industrial waste heat.

[0074] Further, the external heat energy provided by the external heat source and the compression heat energy in the heat storage tank can be jointly output to the regasification air in the charging mode.

[0075] In some embodiments, the liquid air energy storage system in the embodiment of the present application can further include a shallow cooling charging heat exchanger XC-SC, a shallow cooling discharging heat exchanger XD-SC, a shallow cooling tank (such as a hot end D2-SC and a cold end D1-SC), and a shallow cooling medium; wherein the shallow cooling medium cools the ambient air to a shallow cooling temperature SCT in the shallow cooling charging heat exchanger in the LAES charging mode, and the shallow cooling medium is cooled to the shallow cooling temperature SCT by the liquid air in the shallow cooling discharging heat exchanger in the LAES discharging mode and then enters the shallow cooling tank to realize storage of the shallow cooling energy SCE. The flow direction of the shallow cooling medium in the LAES charging and discharging modes is described above and will not be repeated here.

[0076] In some embodiments, the liquid air energy storage system in the embodiments of the present application can further comprise an air purifier APU for adsorbing and removing carbon dioxide, water and other impurities in the ambient air during the charging process. Preferably, the air purifier can be arranged between the normal-temperature compressor C1 and the low-temperature compressor (such as C2, C3, C4). Further, the air purifier APU can be arranged between the heat storage charging heat exchanger XC-H and the low-temperature compressor (such as C2, C3, C4).

[0077] The principle of removing carbon dioxide and water in the ambient air by the air purifier APU can be that the carbon dioxide and water in the ambient air are adsorbed by the molecular sieve, and therefore at least part of the regasified air output by the expander E1 can be discharged to the environment after flowing through the air purifier during the discharging process of the LAES subsystem, and the desorption of carbon dioxide and water in the air purifier APU is completed by using this part of the ambient air, so that the air purifier APU can be cyclically operated during the charging and discharging processes.

[0078] At present, a coupling model of LNG-RG and LAES has appeared in the prior art, mainly because the liquefied natural gas regasification (LNG-RG) process can release a large amount of cold energy; these cold energies can be introduced into the LAES system to improve the liquefaction ratio of air during the charging process and improve the charging and discharging electric efficiency of the LAES system. However, as with the problems encountered in the prior art of liquid air regasification, it is usually directly pressurized to the target pressure of the natural gas under the regasification condition, and then the cold energy released in the liquefied natural gas regasification process is recovered at this target pressure, and the cold energy quality introduced by LNG-RG into the LAES system can be further improved.

[0079] Specifically, the liquid air energy storage system in the embodiments of the present application can further comprise: an LNG ultra-cold charging heat exchanger XC-LUC, an LNG ultra-cold tank (such as a hot end D2-LUC and a cold end D1-LUC), an LNG ultra-cold medium, and a natural gas regasification subsystem, wherein the natural gas regasification subsystem comprises: at least two LNG low-temperature pumps (such as LCP1 and LCP2), an LNG ultra-cold heat exchanger XL-LUC, and an LNG deep cold heat exchanger XL-DC.

[0080] wherein, in the LNG regasification working condition, the LNG is sequentially pressurized by at least two LNG cryogenic pumps to reach the LNG target pressure before LNG regasification; wherein, the LNG is pressurized by a first LNG cryogenic pump LCP1 and then enters an LNG subcooling heat exchanger XL-LUC to cool the LNG subcooling medium to a LNG subcooling temperature LUCT; the LNG subcooling medium at the LNG subcooling temperature LUCT enters an LNG subcooling tank to store LNG subcooling energy LUCE; the LNG is pressurized by a second LNG cryogenic pump LCP2 and then passes through an LNG deep cooling heat exchanger XL-DC to cool the deep cooling medium to a deep cooling temperature DCT; the deep cooling medium at the deep cooling temperature DCT enters a deep cooling tank to store deep cooling energy;

[0081] wherein, in order to reduce the LNG regasification in the LNG subcooling energy and deep cooling energy recovery process, the temperature of the LNG after LNG subcooling energy recovery is lower than the liquid-gas phase transition temperature of the LNG after first pressurization; similarly, the temperature of the LNG after deep cooling energy recovery is lower than the liquid-gas phase transition temperature of the LNG after second pressurization.

[0082] further, in the LAES charging working condition, before the ambient air at the deep cooling temperature is cooled to the air subcooling temperature, the ambient air is first cooled to the LNG subcooling temperature LUCT in the LNG subcooling charging heat exchanger by using the LNG subcooling medium at the LNG subcooling temperature, and then the ambient air is cooled to the air subcooling temperature AUCT in the air subcooling charging heat exchanger by using the air subcooling medium at the air subcooling temperature AUCT.

[0083] In this embodiment, the LNG-RG system is coupled with the LAES system, so that the sufficient cold energy generated in the LNG regasification process of the LNG-RG system can be used to improve the charging and discharging efficiency of the LAES system; in addition, for the LNG-RG system, the LNG in the LNG regasification working condition of the LNG-RG system is sequentially pressurized by the first LNG cryogenic pump and the second LNG cryogenic pump to reach the LNG target pressure before LNG regasification, and the loss of high-quality cold energy caused by one-time pressurization of the LNG to the LNG target pressure is avoided, so that relatively higher-quality cold energy can be obtained after the first pressurization, which can be applied in the LAES system to further improve the charging and discharging efficiency of the LAES system.

[0084] In some embodiments, the natural gas regasification subsystem can further comprise a third LNG cryogenic pump LCP3 located after the first LNG cryogenic pump LCP1 and the second LNG cryogenic pump LCP2, for pressurizing the LNG to a target LNG pressure; and can further comprise an LNG sub-cooling heat exchanger; the LNG, after being pressurized by the third LNG cryogenic pump LCP3, enters the LNG sub-cooling heat exchanger XL-SC to cool the sub-cooling medium to a sub-cooling temperature SCT; and the sub-cooling medium at the sub-cooling temperature SCT enters a sub-cooling tank to store a sub-cooling energy SCE.

[0085] In some embodiments, due to the coupling of the LNG-RG system, the sub-cooling energy from the LNG in the sub-cooling tank is abundant, and a large amount of LNG sub-cooling energy can be output to external applications.

[0086] In some embodiments, the discharge target pressure in the embodiments of the present application is higher than the charging target pressure, which can ensure the cold energy balance between the cold energy consumption in the charging working condition and the cold energy recovery in the discharging working condition of the LAES system at a higher discharge target pressure; in the prior art, the charging target pressure is generally higher than the discharge target pressure to achieve the cold energy balance between the charging working condition and the discharging working condition, especially the air super-cooling energy balance.

[0087] In some embodiments, the air super-cooling tank, the LNG super-cooling tank and the deep-cooling tank in the embodiments of the present application are respectively a pair of adiabatic low-pressure containers; the temperatures of the media stored in the cold-end containers of the air super-cooling tank, the LNG super-cooling tank and the deep-cooling tank are respectively an air super-cooling temperature, an LNG super-cooling temperature and a deep-cooling temperature; the air super-cooling temperature is lower than the LNG super-cooling temperature, and the LNG super-cooling temperature is lower than the deep-cooling temperature.

[0088] In some embodiments, the air super-cooling tank, the LNG super-cooling tank, the deep-cooling tank, the sub-cooling tank and the heat storage tank in the embodiments of the present application can be respectively one or more solid packed beds, comprising a hot-end outlet and a cold-end outlet; during cold storage, the cold energy exchange is performed by the exchange cold medium led out from the hot end to the cold end, while during cold release, the cold energy exchange is performed by the exchange cold medium led out from the cold end to the hot end; the heat storage and heat release processes are the same.

[0089] In some embodiments, the air super-cooling discharge heat exchanger and / or the LNG super-cooling heat exchanger in the embodiments of the present application can be selected as a plate heat exchanger structure to meet the heat exchange between low-pressure fluids, which has the advantages of high heat exchange efficiency and small pinch point temperature difference; other heat exchangers in the embodiments of the present application can be selected as a tube-shell heat exchanger to meet the heat exchange between high-pressure fluids.

[0090] In some embodiments, the liquid air energy storage system in the embodiments of the present application can further comprise: an LNG expander EL for generating power by using re-gasified natural gas; wherein the LNG target pressure is higher than the pressure of the natural gas after re-gasification entering the natural gas pipeline network, and the pressure difference between the LNG target pressure and the pipeline network pressure is used to generate power by the LNG expander EL. The LNG expander EL can also be a multi-stage expander.

[0091] The heat exchange medium, the shallow cooling medium, the deep cooling medium, the LNG supercooling medium and the air supercooling medium in the embodiments of the present application are all heat exchange media, which are used to distinguish different heat exchange cycles. The heat exchange media with stable properties can be selected according to the corresponding heat exchange requirements and scenes, and the present application does not limit this. Preferably, the air supercooling medium, the LNG supercooling medium and the deep cooling medium in the embodiments of the present application can be selected from propane, which has the advantage of stable properties under low temperature conditions.

[0092] Generally, the cold / heat energy exchange by the heat exchanger and the heat exchange medium will inevitably result in the loss of pinch temperature difference, which is the common knowledge in the art and is not the focus of the embodiments of the present application. In order to be brief, the temperature difference loss is not described every time.

[0093] On the other hand, the ambient air reaching the charging target pressure will also have its pressure reduced after further absorbing cold energy, and the flow through the heat exchanger will also cause pressure loss. The liquid air reaching the discharging target pressure is the same. These factors are the common knowledge in the art and are not the focus of the embodiments of the present application. In order to be brief, the influence of these factors on the charging target pressure and the discharging target pressure is not described every time.

[0094] It should be understood by those skilled in the art that the above differences do not affect the coverage and protection of the present application.

[0095] In some embodiments, the quality of the cryogenic energy recovered from the LNG regasification process and the quality of the cryogenic energy recovered from the liquid air regasification process are still different, and directly mixing and storing them in one cryogenic tank will cause some loss of high-quality cold energy. Therefore, an optimization design is proposed in the embodiments of the present application. Specifically, as shown in FIG. 2, the cryogenic tank can be divided into an air cryogenic tank (cold end D1-ADC, hot end D2-ADC) and an LNG cryogenic tank (cold end D1-LDC, hot end D2-LDC), which are independent of each other, the cryogenic charging heat exchanger is divided into an air cryogenic charging heat exchanger XC4-ADC and an LNG cryogenic charging heat exchanger (such as XC1-LDC, XC2-LDC, XC3-LDC), the cryogenic medium is divided into an air cryogenic medium and an LNG cryogenic medium, and the cryogenic discharging heat exchanger can be considered as an air cryogenic discharging heat exchanger. At this time, the air cryogenic tank, the air cryogenic charging heat exchanger and the air cryogenic discharging heat exchanger form a cold exchange cycle with the air cryogenic medium, the LNG cryogenic tank, the LNG cryogenic charging heat exchanger and the LNG cryogenic discharging heat exchanger form a cold exchange cycle with the LNG cryogenic medium, and the two cycles are relatively independent.

[0096] The air cryogenic charging heat exchanger is arranged at the inlet of the low-temperature compressor, and is used for cooling the ambient air before entering the low-temperature compressor to the LNG cryogenic temperature by the LNG cryogenic medium at the LNG cryogenic temperature through the LNG cryogenic charging heat exchanger, so that the low-temperature compressor performs low-temperature compression on the ambient air at the LNG cryogenic temperature. The air cryogenic charging heat exchanger is arranged at the outlet of the low-temperature compressor, and is used for cooling the ambient air discharged from the low-temperature compressor to the air cryogenic temperature by the air cryogenic medium at the air cryogenic temperature through the air cryogenic charging heat exchanger. The air cryogenic temperature is lower than the LNG cryogenic temperature.

[0097] In some embodiments, the air cryogenic charging heat exchanger is used for cooling the ambient air reaching the charging target pressure to the air cryogenic temperature. Further, for a multi-stage low-temperature compressor group composed of multiple low-temperature compressors, the number of LNG cryogenic charging heat exchangers can be multiple, corresponding to the number of low-temperature compressors in the multi-stage low-temperature compressor. An LNG cryogenic charging heat exchanger is arranged at the inlet of each low-temperature compressor, which is used for making the ambient air perform low-temperature compression at the LNG cryogenic temperature by using sufficient LNG cryogenic energy. The air cryogenic charging heat exchanger is arranged at the outlet of the last-stage low-temperature compressor, which is used for cooling the ambient air reaching the charging target pressure to the air cryogenic temperature which is lower than the LNG cryogenic temperature by using limited air cryogenic energy, so that the ambient air continues to gradually cool to the LNG supercooling temperature, to the air supercooling temperature, or directly reaches the air supercooling temperature at the air cryogenic temperature.

[0098] Specifically,

[0099] In the LAES discharging condition, the air cryogenic medium is cooled to the air cryogenic temperature by the air cryogenic heat exchanger after the liquid air is pressurized by the second discharging cryogenic pump therein; the air cryogenic medium at the air cryogenic temperature is stored in the air cryogenic tank;

[0100] In the LNG regasification condition, the LNG cryogenic medium is cooled to the LNG cryogenic temperature by the LNG cryogenic heat exchanger after the LNG is pressurized by the second LNG cryogenic pump therein; the LNG cryogenic medium at the LNG cryogenic temperature is stored in the LNG cryogenic tank;

[0101] In the LAES discharging condition, the ambient air is cooled to the cryogenic temperature by the cryogenic charging heat exchanger using the cryogenic medium at the cryogenic temperature before and after the ambient air enters the cryogenic compressor, specifically including: the ambient air is cooled to the LNG cryogenic temperature by the LNG cryogenic charging heat exchanger using the LNG cryogenic medium at the LNG cryogenic temperature before the ambient air enters the cryogenic compressor, and the ambient air discharged from the cryogenic compressor is cooled to the air cryogenic temperature by the air cryogenic charging heat exchanger using the air cryogenic medium at the air cryogenic temperature.

[0102] The air cryogenic temperature in the embodiment is lower than the LNG cryogenic temperature, so the quality of the air cryogenic energy is higher than that of the LNG cryogenic energy, but the volume of the air cryogenic energy is relatively limited compared with the volume of the LNG cryogenic energy, so how to reasonably use the air cryogenic energy and the LNG cryogenic energy is the key to further improve the overall charging and discharging efficiency of the LAES. In the embodiment of the present application, the LNG cryogenic energy and the air cryogenic energy are relatively independently stored and released, the sufficient LNG cryogenic energy is applied to the pre-cooling of the cryogenic compression, and the air cryogenic energy is applied to the cooling treatment of the ambient air reaching the charging target pressure, and the volume and quality of the LNG cryogenic energy and the air cryogenic energy are comprehensively considered, so that the overall charging and discharging efficiency of the LAES can be further improved.

[0103] In some embodiments, in addition to the above embodiments, the use of the LNG cryogenic energy and the air cryogenic energy can also be determined according to system requirements, which are not limited to using the LNG cryogenic energy alone to cool the ambient air before and after the cryogenic compression, or using the air cryogenic energy alone to cool the ambient air before and after the cryogenic compression, or using the air cryogenic energy first and then using the LNG cryogenic energy, and the present application does not limit this.

[0104] Embodiment 1

[0105] With reference to Fig. 1, a liquid air energy storage system, comprising: ambient temperature compressor C1, regenerative charge heat exchanger XC-H, air purifier APU, sub-cool charge heat exchanger XC-SC, first deep cool charge heat exchanger XC1-DC, first low temperature compressor C2, second deep cool charge heat exchanger XC2-DC, second low temperature compressor C3, third deep cool charge heat exchanger XC3-DC, third low temperature compressor C4, fourth deep cool charge heat exchanger XC4-DC, LNG ultra cool charge heat exchanger XC-LUC, air ultra cool charge heat exchanger XC-AUC, cryogenic expander CE, liquid air separator LAS, liquid air storage tank LAD, first discharge cryogenic pump DCP1, air ultra cool discharge heat exchanger XD-AUC, second discharge cryogenic pump DCP2, deep cool discharge heat exchanger XD-DC, sub-cool discharge heat exchanger XD-SC, regenerative discharge heat exchanger XD-H, expander E1, regenerative tank (hot end D1-H, cold end D2-H), sub-cool tank (hot end D1-SC, cold end D2-SC), deep cool tank (hot end D1-DC, cold end D2-DC), LNG ultra cool tank (hot end D1-LUC, cold end D2-LUC), air ultra cool tank (hot end D1-AUC, cold end D2-AUC) and natural gas regasification subsystem;

[0106] Ambient temperature compressor C1, regenerative charge heat exchanger XC-H, air purifier APU, sub-cool charge heat exchanger XC-SC, first deep cool charge heat exchanger XC1-DC, first low temperature compressor C2, second deep cool charge heat exchanger XC2-DC, second low temperature compressor C3, third deep cool charge heat exchanger XC3-DC, third low temperature compressor C4, fourth deep cool charge heat exchanger XC4-DC, LNG ultra cool charge heat exchanger XC-LUC, air ultra cool charge heat exchanger XC-AUC, cryogenic expander CE, liquid air separator LAS and liquid air storage tank LAD constitute air liquefaction path and flow direction under charge condition.

[0107] Liquid air storage tank LAD, first discharge cryogenic pump DCP1, air ultra cool discharge heat exchanger XD-AUC, second discharge cryogenic pump DCP2, deep cool discharge heat exchanger XD-DC, sub-cool discharge heat exchanger XD-SC, regenerative discharge heat exchanger XD-H and expander E1 constitute liquid air regasification path and flow direction under discharge condition.

[0108] Natural gas regasification subsystem, comprising: first LNG cryogenic pump LCP1, LNG ultra cool heat exchanger XL-LUC, second LNG cryogenic pump LCP2, LNG deep cool heat exchanger XL-DC, third LNG cryogenic pump LCP3, LNG sub-cool heat exchanger XL-SC and LNG expander EL, constituting natural gas regasification path and flow direction.

[0109] The air overcooling charging heat exchanger XC-AUC, the air overcooling discharging heat exchanger XD-AUC, and the air overcooling tank (hot end D2-AUC and cold end D1-AUC) constitute a cold exchange cycle for cold energy exchange with air overcooling medium; the LNG overcooling charging heat exchanger XC-LUC, the LNG overcooling heat exchanger XL-LUC, and the LNG overcooling tank (hot end D2-LUC and cold end D1-LUC) constitute a cold exchange cycle for cold energy exchange with LNG overcooling medium; the first deep cooling charging heat exchanger XC1-DC, the second deep cooling charging heat exchanger XC2-DC, the third deep cooling charging heat exchanger XC3-DC, the fourth deep cooling charging heat exchanger XC4-DC, the deep cooling discharging heat exchanger XD-DC, the LNG deep cooling heat exchanger XL-DC, and the deep cooling tank (hot end D2-DC and cold end D1-DC) constitute a cold exchange cycle for cold energy exchange with deep cooling medium; the shallow cooling charging heat exchanger XC-SC, the shallow cooling discharging heat exchanger XD-SC, and the shallow cooling tank (hot end D2-SC and cold end D2-SC) constitute a cold exchange cycle for cold energy exchange with shallow cooling medium; and the heat storage charging heat exchanger XC-H, the heat storage discharging heat exchanger XD-H, and the heat storage tank (hot end D2-H and cold end D1-H) constitute a heat exchange cycle for heat energy exchange with heat exchange medium.

[0110] The air overcooling tank, the LNG overcooling tank, the deep cooling tank, the shallow cooling tank, and the heat storage tank in the embodiment are one or more pairs of adiabatic low-pressure containers, which are the hot end and the cold end of the tank body; during cold storage, the cold exchange medium is guided from the hot end to the cold end for cold energy exchange, and during cold release, the cold exchange medium is guided from the cold end to the hot end for cold energy exchange; the heat storage and heat release processes are the same. Specifically, the air overcooling tank includes an air overcooling tank cold end D1-AUC and an air overcooling tank hot end D2-AUC; the LNG overcooling tank includes an LNG overcooling tank cold end D1-LUC and an LNG overcooling tank hot end D2-LUC; the deep cooling tank includes a deep cooling tank cold end D1-DC and a deep cooling tank hot end D2-DC; the shallow cooling tank includes a shallow cooling tank cold end D1-SC and a shallow cooling tank hot end D2-SC; and the heat storage tank includes a heat storage tank cold end D1-H and a heat storage tank hot end D2-H.

[0111] In the charging working condition, the ambient air liquefaction path is operated and the liquid air gasification path is closed; the ambient air first enters the normal temperature compressor C1 to be compressed at normal temperature, and then the compressed heat energy of the ambient air is recovered by the heat storage medium through the heat storage charging heat exchanger XC-H for storage, and the ambient air after outputting the compressed heat energy continues to enter the air purifier APU to remove the impurities such as carbon dioxide and water, and then is cooled to a sub-cooling temperature by the sub-cooling medium through the sub-cooling charging heat exchanger XC-SC, and then is cooled to a deep cooling temperature by the deep cooling medium through the first deep cooling charging heat exchanger XC1-DC, so as to enter the first low temperature compressor C2 to be compressed at a deep cooling temperature and be heated, and then is cooled to a deep cooling temperature by the deep cooling medium through the second deep cooling charging heat exchanger XC2-DC, and continues to enter the second low temperature compressor C3 to be compressed at a deep cooling temperature and be heated, and then is cooled to a deep cooling temperature by the deep cooling medium through the third deep cooling charging heat exchanger XC3-DC, and continues to enter the third low temperature compressor C4 to be compressed at a deep cooling temperature and be heated, and then is cooled to a deep cooling temperature by the deep cooling medium through the fourth deep cooling charging heat exchanger XC4-DC, and then is cooled to a LNG ultra-cooling temperature by the LNG ultra-cooling medium through the LNG ultra-cooling charging heat exchanger XC-LUC, and then is cooled to an air ultra-cooling temperature by the air ultra-cooling medium through the air ultra-cooling charging heat exchanger XC-AUC, so as to enter the low temperature expander CE to be expanded at an air ultra-cooling temperature, so as to obtain gas-liquid mixed air, and the liquid air is separated out from the liquid air separator LAS and is stored in the liquid air storage tank LAD, and the backflow air AIR UC separated out from the liquid air separator LAS can be used to recover the cold energy in stages, or can be used as a cold source to maintain the deep cooling environment of the low temperature compression system.

[0112] In the above process, the heat storage medium enters the heat storage charging heat exchanger XC-H from the cold end D1-H of the heat storage tank to absorb the compressed heat energy of the ambient air, and then enters the hot end D2-H of the heat storage tank; the sub-cooling medium enters the sub-cooling charging heat exchanger XC-SC from the cold end D1-SC of the sub-cooling tank to cool the ambient air, and then enters the hot end D2-SC of the sub-cooling tank; the deep cooling medium enters the first deep cooling charging heat exchanger XC1-DC, the second deep cooling charging heat exchanger XC2-DC, the third deep cooling charging heat exchanger XC3-DC and the fourth deep cooling charging heat exchanger XC4-DC from the cold end D1-DC of the deep cooling tank to cool the ambient air, and then enters the hot end D2-DC of the deep cooling tank; the LNG ultra-cooling medium enters the LNG ultra-cooling charging heat exchanger XC-LUC from the cold end D1-LUC of the LNG ultra-cooling tank to cool the ambient air, and then enters the hot end D2-LUC of the LNG ultra-cooling tank; and the air ultra-cooling medium enters the air ultra-cooling charging heat exchanger XC-AUC from the cold end D1-AUC of the air ultra-cooling tank to cool the ambient air, and then enters the hot end D2-AUC of the air ultra-cooling tank.

[0113] In the discharging condition, the air liquefaction path is closed, and the liquid air regasification path is operated; the liquid air is firstly released from the liquid air storage tank LAD, then pressurized by the first discharging cryogenic pump DCP1, and then cooled by the air supercooling discharging heat exchanger XD-AUC to the air supercooling temperature to store the air supercooling medium and warm the liquid air, and then pressurized by the second discharging cryogenic pump DCP2 to the discharging target pressure, and then cooled by the deep cooling discharging heat exchanger XD-DC to the deep cooling temperature to store the deep cooling medium and continue to warm the liquid air, and then cooled by the shallow cooling discharging heat exchanger XD-SC to the shallow cooling temperature to store the shallow cooling medium and again warm the liquid air to produce regasification air, and then expanded by the heat storage discharging heat exchanger XD-H to absorb the compression heat of the heat storage medium, and finally enter the expander E1 to generate power. The expander is a multi-stage expansion, which is not described here.

[0114] In the above process, the air supercooling medium enters the air supercooling discharging heat exchanger XD-AUC from the air supercooling tank hot end D2-AUC to absorb the cold energy in the liquid air, and then enters the air supercooling tank cold end D1-AUC. The deep cooling medium enters the deep cooling discharging heat exchanger XD-DC from the deep cooling tank hot end D2-DC to absorb the cold energy in the liquid air, and then enters the deep cooling tank cold end D1-DC; the shallow cooling medium enters the shallow cooling discharging heat exchanger XD-SC from the shallow cooling tank hot end D2-SC to absorb the cold energy in the liquid air, and then enters the shallow cooling tank cold end D1-SC; the heat storage medium enters the heat storage discharging heat exchanger XD-H from the heat storage tank hot end D2-H to warm the liquid air, and then enters the heat storage tank cold end D1-H.

[0115] In the natural gas regasification condition, the natural gas regasification path is operated; the liquefied natural gas firstly passes through the first LNG cryogenic pump LCP1 to be pressurized, then passes through the LNG supercooling heat exchanger XL-LUC to be cooled by the LNG supercooling medium to the LNG supercooling temperature to store the LNG supercooling medium and warm the liquefied natural gas, and then passes through the second LNG cryogenic pump LCP2 to be pressurized, then passes through the LNG deep cooling heat exchanger XL-DC to be cooled by the deep cooling medium to the deep cooling temperature to store the deep cooling medium and continue to warm the liquefied natural gas, and then passes through the third LNG cryogenic pump LCP3 to be pressurized to the LNG target pressure, then passes through the LNG shallow cooling heat exchanger XL-SC to be cooled by the shallow cooling medium to the shallow cooling temperature to store the shallow cooling medium and continue to warm the liquefied natural gas to achieve regasification, and finally the regasified natural gas enters the LNG expander EL to generate power, and then outputs the regasified natural gas. The LNG expander is a multi-stage expansion, which is not described here.

[0116] In the above process, the LNG super-cooling medium enters the LNG super-cooling tank from the hot end D2-LUC, absorbs the cold energy in the liquefied natural gas in the LNG super-cooling heat exchanger XL-LUC, and then enters the cold end D1-LUC of the LNG super-cooling tank. The deep-cooling medium enters the LNG deep-cooling heat exchanger XL-DC from the hot end D2-DC, absorbs the cold energy in the liquefied natural gas, and then enters the cold end D1-DC of the deep-cooling tank. The shallow-cooling medium enters the LNG shallow-cooling heat exchanger XL-SC from the hot end D2-SC, absorbs the cold energy in the liquefied natural gas, and then enters the cold end D1-SC of the shallow-cooling tank.

[0117] Embodiment 2

[0118] With continuous reference to FIG. 2, the liquid air energy storage system in this embodiment is based on Embodiment 1, and the deep-cooling tank is divided into an LNG deep-cooling tank (cold end D1-LDC and hot end D2-LDC) and an air deep-cooling tank (cold end D1-ADC and hot end D2-ADC), and the deep-cooling charging heat exchanger is divided into a first LNG deep-cooling charging heat exchanger XC1-LDC, a second LNG deep-cooling charging heat exchanger XC2-LDC, a third LNG deep-cooling charging heat exchanger XC3-LDC, and an air deep-cooling charging heat exchanger XC4-ADC. Among them, the LNG deep-cooling tank, the first LNG deep-cooling charging heat exchanger XC1-LDC, the second LNG deep-cooling charging heat exchanger XC2-LDC, the third LNG deep-cooling charging heat exchanger XC3-LDC, and the LNG deep-cooling heat exchanger constitute a cold exchange cycle for exchanging cold energy with the LNG deep-cooling medium; the air deep-cooling tank, the air deep-cooling charging heat exchanger, and the air deep-cooling discharging heat exchanger constitute a cold exchange cycle for exchanging cold energy with the air deep-cooling medium.

[0119] In the charging condition, the ambient air liquefaction path is operated and the liquid air regasification path is closed; the ambient air first enters the normal temperature compressor C1 for normal temperature compression, and then the compressed heat energy of the ambient air is recovered by the heat storage medium through the heat storage charging heat exchanger XC-H for storage, and the ambient air after outputting the compressed heat energy continues to enter the air purifier APU to remove the impurities such as carbon dioxide and water, and then is cooled to the sub-cooling temperature by the sub-cooling medium through the sub-cooling charging heat exchanger XC-SC, and then is cooled to the LNG deep cooling temperature by the LNG deep cooling medium through the first LNG deep cooling charging heat exchanger XC1-LDC, so as to enter the first low temperature compressor C2 for the first low temperature compression and temperature rise at the LNG deep cooling temperature, and then is cooled to the LNG deep cooling temperature by the LNG deep cooling medium through the second LNG deep cooling charging heat exchanger XC2-LDC, continues to enter the second low temperature compressor C3 for the second low temperature compression and temperature rise at the LNG deep cooling temperature, and then is cooled to the LNG deep cooling temperature by the LNG deep cooling medium through the third LNG deep cooling charging heat exchanger XC3-LDC, continues to enter the third low temperature compressor C4 for the third low temperature compression to reach the charging target pressure and temperature rise, and then is cooled to the air deep cooling temperature by the air deep cooling medium through the air deep cooling charging heat exchanger XC4-ADC, and then is cooled to the LNG ultra-cooling temperature by the LNG ultra-cooling medium through the LNG ultra-cooling charging heat exchanger XC-LUC, and then is cooled to the air ultra-cooling temperature by the air ultra-cooling medium through the air ultra-cooling charging heat exchanger XC-AUC, enters the low temperature expander CE for low temperature expansion at the air ultra-cooling temperature, so as to obtain the gas-liquid mixed air, and the liquid air is separated out from the liquid air separator LAS and stored in the liquid air storage tank LAD, and the backflow air AIR UC separated from the liquid air separator LAS can be used for gradient recovery of cold energy or can be used as a cold source to maintain the LNG deep cooling temperature environment of the low temperature compression system.

[0120] In the discharging condition, the air liquefaction path is closed and the liquid air regasification path is operated; the liquid air is first released from the liquid air storage tank LAD, and then is pressurized by the first discharging low temperature pump DCP1, and then the air ultra-cooling medium is cooled to the air ultra-cooling temperature by the air ultra-cooling discharging heat exchanger XD-AUC for storage to heat the liquid air, and then the heated liquid air is pressurized to the discharging target pressure by the second discharging low temperature pump DCP2, and then the air deep cooling medium is cooled to the air deep cooling temperature by the air deep cooling discharging heat exchanger XD-ADC for storage to continue heating the liquid air, and then the sub-cooling medium is cooled to the sub-cooling temperature by the sub-cooling discharging heat exchanger XD-SC for storage to heat the liquid air again to produce regasification air, and then the regasification air is expanded by absorbing the compressed heat energy of the heat exchange medium through the heat storage discharging heat exchanger XD-H, and finally enters the expander E1 to generate power.

[0121] In the natural gas regasification working condition, the natural gas regasification path is operated; the liquefied natural gas is first pressurized by a first LNG cryogenic pump LCP1 along the natural gas regasification path, then cooled to a LNG supercooling temperature by a LNG supercooling heat exchanger XL-LUC to store the LNG supercooling medium to warm up the liquefied natural gas, and then pressurized by a second LNG cryogenic pump LCP2, and then cooled to a LNG deep cooling temperature by a LNG deep cooling heat exchanger XL-LDC to store the LNG deep cooling medium to continue to warm up the liquefied natural gas, and then pressurized by a third LNG cryogenic pump LCP3 to a LNG target pressure to continue to warm up the liquefied natural gas by a LNG shallow cooling heat exchanger XL-SC to a shallow cooling temperature to store the shallow cooling medium to realize regasification, and finally, the regasified natural gas is used to drive a LNG expander EL to generate power, and then output to the outside.

[0122] The transfer of the heat exchange medium in the charging, discharging and regasification processes in the corresponding tank is the same as the foregoing principle, and will not be described here again.

[0123] The embodiment of the application also establishes a system data model for the liquid air energy storage system of the embodiment 2, and part of the unit nodes in the system model are shown in Fig. 3, and the operating parameter design of the unit nodes can be understood in combination with the following table:

[0124] After the simulation calculation of the system model with the foregoing operating parameters, the power consumption of the main components of the system is shown in the following table; wherein, the expander is a three-stage expander set, including: a first expander E1, a second expander E2 (not shown) and a third expander E3 (not shown). The LNG expander is a two-stage expander set, including: a first LNG expander EL1 and a second LNG expander EL2 (not shown).

[0125] From the foregoing data, it can be known that the charging and discharging efficiency of the liquid air energy storage system in the embodiment of the application reaches 96.78%.

[0126] The embodiment of the application also discloses a liquid air energy storage method, including: a LAES discharging working condition and a LAES charging working condition.

[0127] In the LAES discharging working condition, the liquid air performs the following steps:

[0128] C1, the liquid air is pressurized by a first discharging cryogenic pump;

[0129] C2, the liquid air is cooled to an air supercooling temperature by an air supercooling discharging heat exchanger; wherein, the air supercooling medium at the air supercooling temperature is stored in an air supercooling tank;

[0130] C3, the liquid air is pressurized by the second discharge cryogenic pump to reach the discharge target pressure before the liquid air is re-gasified;

[0131] C4, the liquid air is cooled by the cryogenic discharge heat exchanger to the cryogenic temperature; wherein, the cryogenic temperature cryogenic medium enters the cryogenic tank for storage;

[0132] In the LAES charging condition, the ambient air performs the following steps:

[0133] D1, the ambient air is compressed by the cryogenic compressor to the charging target pressure before the ambient air is liquefied; wherein, the ambient air is cooled to the cryogenic temperature by the cryogenic charging heat exchanger using the cryogenic temperature cryogenic medium before and after entering the cryogenic compressor;

[0134] D2, the ambient air at the target charging pressure is further cooled to the air supercooling temperature by the air supercooling charging heat exchanger using the air supercooling medium at the air supercooling temperature;

[0135] D3, the ambient air at the air supercooling temperature is converted into liquid air at normal pressure by the cryogenic expander;

[0136] Wherein, the cold end temperature of the air supercooling tank is the air supercooling temperature, and the cold end temperature of the cryogenic tank is the cryogenic temperature; the air supercooling temperature is lower than the cryogenic temperature.

[0137] In some embodiments, the liquid air energy storage method can further include: LNG re-gasification condition;

[0138] In the LNG re-gasification condition, the LNG performs the following steps:

[0139] L1, the LNG is pressurized by the first LNG cryogenic pump;

[0140] L2, the LNG is cooled by the LNG supercooling heat exchanger to the LNG supercooling temperature; wherein, the LNG supercooling medium at the LNG supercooling temperature enters the LNG supercooling tank for storage;

[0141] L3, the LNG is pressurized by the second LNG cryogenic pump to reach the LNG target pressure before the LNG is re-gasified;

[0142] L4, the LNG is cooled by the LNG cryogenic heat exchanger to the cryogenic temperature; the cryogenic medium at the cryogenic temperature enters the cryogenic tank for storage;

[0143] Wherein, in the LAES discharge condition, the D2 includes:

[0144] D2-1, first, ambient air at a deep cooling temperature reaching a charging target pressure is cooled to an LNG subcooling temperature by using LNG subcooling medium of LNG subcooling temperature of LNG subcooling charge heat exchanger;

[0145] D2-2, ambient air at LNG subcooling temperature is further cooled to air subcooling temperature by using air subcooling medium of air subcooling temperature of air subcooling charge heat exchanger;

[0146] Wherein, the LNG subcooling temperature is lower than the deep cooling temperature and higher than the air subcooling temperature.

[0147] In some embodiments, the discharging target pressure is higher than the charging target pressure.

[0148] The above-mentioned liquid air energy storage method in the embodiments of the present application only shows the key steps concerned by the present application, and in addition to the above steps, other process steps can also be included, and specific reference can be made to the related description in the system embodiments.

[0149] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A liquid air energy storage system, characterized in that, The system comprises: a cryogenic compressor, a cryogenic expander, at least two discharge cryogenic pumps, an air supercooling discharge heat exchanger, an air supercooling charge heat exchanger, an air supercooling tank, an air supercooling medium, a deep cooling discharge heat exchanger, a deep cooling charge heat exchanger, a deep cooling tank and a deep cooling medium; wherein, under LAES discharge condition, liquid air is sequentially pressurized by the at least two discharge cryogenic pumps to a discharge target pressure before liquid air regasification; after liquid air is pressurized by a first discharge cryogenic pump therein, the air supercooling medium is cooled to an air supercooling temperature by the air supercooling discharge heat exchanger; the air supercooling medium at the air supercooling temperature is stored in the air supercooling tank; after liquid air is pressurized by a second discharge cryogenic pump therein, the deep cooling medium is cooled to a deep cooling temperature by the deep cooling discharge heat exchanger; the deep cooling medium at the deep cooling temperature is stored in the deep cooling tank; wherein, under LAES charge condition, ambient air is compressed by the cryogenic compressor to a charge target pressure before ambient air liquefaction; ambient air is cooled to a deep cooling temperature by the deep cooling charge heat exchanger using the deep cooling medium at the deep cooling temperature before and after entering the cryogenic compressor; the deep cooling temperature ambient air at the charge target pressure is further cooled to an air supercooling temperature by the air supercooling charge heat exchanger using the air supercooling medium at the air supercooling temperature; the air supercooling temperature ambient air is converted into liquid air at normal pressure by the cryogenic expander.

2. A liquid air energy storage system according to claim 1, wherein, Further comprising: an LNG supercooling charge heat exchanger, an LNG supercooling tank, an LNG supercooling medium and a natural gas regasification subsystem; the natural gas regasification subsystem comprises: at least two LNG cryogenic pumps, an LNG supercooling heat exchanger and an LNG deep cooling heat exchanger; wherein, under LNG regasification condition, LNG is sequentially pressurized by the at least two LNG cryogenic pumps to an LNG target pressure before LNG regasification; after LNG is pressurized by a first LNG cryogenic pump therein, the LNG supercooling medium is cooled to an LNG supercooling temperature by the LNG supercooling heat exchanger; the LNG supercooling medium at the LNG supercooling temperature is stored in the LNG supercooling tank; after LNG is pressurized by a second LNG cryogenic pump therein, the deep cooling medium is cooled to a deep cooling temperature by the LNG deep cooling heat exchanger; the deep cooling medium at the deep cooling temperature is stored in the deep cooling tank; wherein, under LAES discharge condition, before the deep cooling temperature ambient air at the charge target pressure is cooled to the air supercooling temperature, the ambient air is first cooled to an LNG supercooling temperature by the LNG supercooling charge heat exchanger using the LNG supercooling medium at the LNG supercooling temperature; wherein, the LNG supercooling temperature is lower than the deep cooling temperature and higher than the air supercooling temperature.

3. The liquid air energy storage system of claim 1, wherein, The discharge target pressure is higher than the charge target pressure.

4. The liquid air energy storage system of claims 1-2, wherein, The cryogenic compressor comprises a plurality of cryogenic compressors, the deep cooling charge heat exchanger comprises a plurality of deep cooling charge heat exchangers, The ambient air reaches the target charging pressure through sequential multi-stage compression of the plurality of low-temperature compressors, and the ambient air is cooled to a cryogenic temperature by a cryogenic medium at a cryogenic temperature through a cryogenic charging heat exchanger before and after entering each stage of the low-temperature compressors.

5. The liquid air energy storage system of claims 1-2, wherein, The air subcooling tank, the LNG subcooling tank and the cryogenic tank are respectively a pair of adiabatic low-pressure containers; the medium stored in the cold-end container of the air subcooling tank, the LNG subcooling tank and the cryogenic tank has an air subcooling temperature, an LNG subcooling temperature and a cryogenic temperature respectively; the air subcooling temperature is lower than the LNG subcooling temperature, and the LNG subcooling temperature is lower than the cryogenic temperature.

6. The liquid air energy storage system of claim 2, wherein, The LNG expander is further included, wherein the LNG target pressure is higher than the pressure of natural gas entering a natural gas pipeline network after regasification, and a pressure difference between the LNG target pressure and the pipeline network pressure is used to do work by the LNG expander.

7. The liquid air energy storage system of claims 1-2, wherein, The air subcooling discharge heat exchanger and / or the LNG subcooling heat exchanger is a plate heat exchanger structure.

8. The liquid air energy storage system of claim 2, wherein, The number of the LNG low-temperature pumps is three.

9. The liquid air energy storage system of claim 2, wherein, The cryogenic charging heat exchanger includes an LNG cryogenic charging heat exchanger at the inlet of the low-temperature compressor and an air cryogenic charging heat exchanger at the outlet of the low-temperature compressor; the cryogenic tank includes an air cryogenic tank and an LNG cryogenic tank which are independent of each other; the cryogenic discharge heat exchanger is an air cryogenic discharge heat exchanger; and the cryogenic medium includes air cryogenic medium and LNG cryogenic medium. In the LAES discharge condition, After the liquid air is pressurized by the second discharge low-temperature pump therein, the air cryogenic medium is cooled to an air cryogenic temperature by the air cryogenic discharge heat exchanger; and the air cryogenic medium at the air cryogenic temperature is stored in the air cryogenic tank; In the LNG regasification condition, After the LNG is pressurized by the second LNG low-temperature pump therein, the LNG cryogenic medium is cooled to an LNG cryogenic temperature by the LNG cryogenic heat exchanger; and the LNG cryogenic medium at the LNG cryogenic temperature is stored in the LNG cryogenic tank; The air cryogenic temperature is lower than the LNG cryogenic temperature. In the LAES discharge condition, the ambient air is cooled to a cryogenic temperature by a cryogenic medium at a cryogenic temperature through a cryogenic charging heat exchanger before and after entering the low-temperature compressor, and the ambient air is cooled to an air subcooling temperature by air subcooling medium at the air subcooling temperature through an air subcooling charging heat exchanger and / or is cooled to an LNG subcooling temperature by LNG subcooling medium at the LNG subcooling temperature through an LNG subcooling charging heat exchanger. It includes:

10. A liquid air energy storage method, characterized by, The LAES discharge condition and the LAES charging condition; In the LAES discharge condition, the liquid air performs the following steps: C1, the liquid air is pressurized by a first discharge low-temperature pump; C2, the liquid air is cooled to air subcooling medium at an air subcooling temperature by an air subcooling discharge heat exchanger; and the air subcooling medium at the air subcooling temperature is stored in an air subcooling tank; C3, the liquid air is pressurized by a second discharge low-temperature pump to reach a discharge target pressure before regasification of the liquid air; ​ C4, liquid air is cooled to a cryogenic temperature by a cryogenic heat exchanger with a cryogenic medium; wherein the cryogenic medium at the cryogenic temperature is stored in a cryogenic tank; In LAES charging condition, ambient air is processed as follows: D1, ambient air is compressed to a charging target pressure before liquefaction of ambient air by a cryogenic compressor; wherein ambient air is cooled to a cryogenic temperature by a cryogenic charging heat exchanger with a cryogenic medium at the cryogenic temperature before and after entering the cryogenic compressor; D2, ambient air at the cryogenic temperature reaching the target charging pressure is further cooled to an air supercooling temperature by an air supercooling charging heat exchanger with an air supercooling medium at the air supercooling temperature; D3, ambient air at the air supercooling temperature is converted to liquid air at normal pressure by a cryogenic expander; Wherein, the cold end temperature of the air supercooling tank is the air supercooling temperature, and the cold end temperature of the cryogenic tank is the cryogenic temperature; the air supercooling temperature is lower than the cryogenic temperature.

11. A liquid air energy storage method according to claim 10, wherein, Further comprising: LNG regasification condition; In LNG regasification condition, LNG is processed as follows: L1, LNG is pressurized by a first LNG cryogenic pump; L2, LNG is cooled to a LNG supercooling temperature by a LNG supercooling heat exchanger with a LNG supercooling medium at the LNG supercooling temperature; wherein the LNG supercooling medium at the LNG supercooling temperature is stored in a LNG supercooling tank; L3, LNG is pressurized by a second LNG cryogenic pump to a target pressure of LNG before LNG regasification; L4, LNG is cooled to a cryogenic temperature by a LNG cryogenic heat exchanger with a cryogenic medium at the cryogenic temperature; wherein the cryogenic medium at the cryogenic temperature is stored in the cryogenic tank; Wherein, in LAES discharging condition, the D2 comprises: D2-1, ambient air at the cryogenic temperature reaching the charging target pressure is first cooled to a LNG supercooling temperature by a LNG supercooling charging heat exchanger with a LNG supercooling medium at the LNG supercooling temperature; D2-2, ambient air at the LNG supercooling temperature is further cooled to an air supercooling temperature by an air supercooling charging heat exchanger with an air supercooling medium at the air supercooling temperature; Wherein, the LNG supercooling temperature is lower than the cryogenic temperature and higher than the air supercooling temperature.

12. The liquid air energy storage method of claim 10, wherein, The discharging target pressure is higher than the charging target pressure.

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